After having recently dropped an almost-insane sum of €94 for a small black plastic clamshell filled with a few painted colour chips, I felt that in order to gain some value for the hard-earned money spent, I had no choice but to to delve further into this and learn more to try to separate the chaff from the wheat. Not only for my own benefit but also for others who are trying to wrap their heads around this concept of camera profiling…
Umm… now it’s becoming really confusing! If the above is true, then perhaps to prevent any misunderstandings, in the same tone of the original title it would be much better to call it:
"Profiling a camera with darktable chart: Figure out how to make your RAWs look like your camera’s jpegs"
The confusion comes from having read the following:
What is “most”? What is one to do if one’s conditions fall outside of this definition yet the desire is still to benefit from camera profiling? Don’t forget that the term “conditions” used in this sense can be highly subjective!
The author is to be commended for his outstanding and generous effort into producing this article. It has undoubtedly been very helpful to guide and inspire me to learn more. However, since it it now appears that the author’s primary purpose was to show how to replicate an OEM’s subjective interpretation of a “pleasing” output, others may also be left scratching their heads just as I was after assuming the article implied a workflow to develop camera profiles to produce real-world results. So, in the spirit of Contribution, here’s what I’ve surmised up to this point:
Why are cameras profiled?
- to enable the OEMs to convert Raw data into ‘pretty’ jpegs
- to stop beginners complaining that their favourite raw processor doesn’t produce results like the pretty jpegs regurgitated by their camera
- to be able to produce “accurate” results by inputting real-world colour values prior to any additional post processing tweaks, if so desired (while not forgetting the attendant critical factors of monitor and printer profiling, of course)
"But I like the OEM’s pretty jpegs"
Well then, as one of the earlier posters suggested, embrace the jpeg and be done with it! Or, if you feel adventurous, work the funky RAW further until you’re satisfied. However, there is something very important that you must keep in mind:
- Each OEM has a different interpretation of “pretty”. In fact, pretty may even mean something all together different across the range of an OEM’s individual models.
In order to see the effect of the above, consider the following:
You and your buddy have been asked by your cousin to shoot her wedding. Somewhere you’ve heard that it’s important to “profile your camera”. As a conscientious photographer you do some research and then follow the steps found in an impressive and highly detailed article. After the wedding, when you begin to process the RAW shots taken by you and your ‘second’, you get an unsettling queasy feeling deep within the pit of your stomach: your cousin the perfectionist is going to flip because the colour of her dress isn’t the same in the various shots! That seems impossible; you took all the right steps:
- you profiled your cameras
- you shot in Raw
- you even used a proper grey card (not an 18% grey) for white balancing all 4 cameras!
This is a classic apples vs oranges conundrum: Camera 1 was shooting apples, camera 2 shot oranges, camera 3 captured grapes and, finally, camera 4 recorded kumquats. Because of their OEM’s unique subjective settings, they all had different reference points which, in turn, produced different pretty results!
The only way to ensure consistency is to begin from consistency. Use a consistent reference. As far as I know, there is nothing more consistent than reality. For example, “real” colours (*let’s not get into “alternate” reality ).
Profiling a camera with darktable-chart: On the way to producing accurate colour results
All right, so this is what I thought that the article was going to be about! Since it wasn’t and since I’m almost certain that many others would also be interested in this, perhaps we can now move forward. In so doing, I hope that the following notes (assumptions!) might help. At the very least, they should serve as springboards for ardent collaborative discussion (vehement disagreement?), correction and consensus leading to something which we may all benefit from:
- Shooting jpegs is unnecessary for this workflow
- Setting proper (or ‘best’) in-camera white balance isn’t necessary since we’re only working with RAW files
- Proper exposure is necessary(!) to prevent clipping so that all of the sample’s data can be analysed. Use an 18% grey card to adjust your camera’s exposure accordingly.
- A set of ISO-delineated ICCs has limited effectiveness if colour accuracy is your goal. If this is indeed your goal, conduct a proper camera profiling workflow for the environment encountered in each shooting session.
Here are some links which may be relevant and of interest. Hopefully somebody much smarter than I am can glean some useful information within:
- Graham Gill’s (ArgyllCMS) camera profiling notes: http://www.argyllcms.com/doc/Scenarios.html#PS1
- Thorough target preparation comments by imatest: http://www.imatest.com/docs/colorcheck/
- “Ghetto” ColourChecker. Dubious yet the most promising DIY target for those who are cheap and don’t mind living on the wild side: https://www.youtube.com/watch?v=6v5wexwSsw4
- X-Rite’s process: https://www.youtube.com/watch?v=CTlugQd3L5g